Olfactory Function Assessment: Standardization of a New Quantitative Technique for the Indian Population

Aim: Olfactory function assessment is often neglected in clinical settings due to a lack of appropriate cost effective techniques. We therefore aimed to develop a cost effective, reliable and culturally appropriate tool for olfactory function assessment among the Indian population and to compare olfactory functions among 63 healthy controls and 32 idiopathic Parkinson’s disease patients. Materials and Methods: Olfactory stimuli were applied to the nostrils of the participants using an olfactometer. Five different odoriferous substances common to Indian culture were used for the study in three different concentrations: ginger (1%, 2%, 3%), cardamom (0.4%, 2%, 3%), garlic (0.8%, 1.4%, 2%), coffee (1.6%, 2%, 4%), vanilla (2%, 3%, 4%). Olfactory recognition threshold, olfactory identification score and olfactory discrimination score were observed among the control population and Parkinson’s disease population. Results: The olfactory recognition threshold was significantly high among the Parkinson’s disease group compared to controls (Mann Whitney U test, p<0.001). Reliability was tested using the test-retest method among the control group and all olfactory variables in three different concentrations had either r value closer to 1 or 1, which shows an acceptable level of reliability. The correlation was found to be significant (p<0.001). A receiver operating characteristic (ROC) curve drawn for olfactory recognition thresholds at different concentrations for the five odouriferous substances and the area was determined to classify cases and controls (Determined areas: ginger = 0.928, cardamom = 0.955, garlic = 0.921, Coffee = 0.950, vanilla = 0.950). The area under the curve was found to be significant in classifying the cases and the control. Conclusion: The newly developed olfactory assessment tool was found to be reliable and effective in assessing olfactory parameters like recognition threshold, identification score and discrimination score among the Indian population.

The whole body transcriptome of Coleophora obducta reveals important olfactory proteins

Background The tiny casebearer moth Coleophora obducta, an important defoliator of Larix spp., is a major threat to ecological security in north China. Studies have shown that C. obducta is strongly specific to host plants; it is unable complete its life cycle without Larix spp. The sex pheromones of C. obducta Z5-10:OH have been elucidated; and eight types of antennae sensilla, have been detected, indicating that an exploration of its olfactory proteins is necessary, due to the general lack of information on this topic. Methods We investigated the whole body transcriptome of C. obducta, performed a phylogenetic analysis of its olfactory proteins and produced expression profiles of three pheromone-binding proteins (CobdPBPs) by qRT–PCR. Results We identified 16 odorant binding proteins, 14 chemosensory proteins, three sensory neuron membrane proteins, six odorant degrading enzymes, five antennal esterases, 13 odorant receptors, seven ionotropic receptors and 10 gustatory receptors, including three PBPs and one odorant co-receptor. Additionally, three putative pheromone receptors, two bitter gustatory receptors and five functional ionotropic receptors were found by phylogenetic analysis. The expression profiles of three PBPs in males and females showed that all of them exhibited male-specific expression and two were expressed at significantly higher levels in males. These data provide a molecular foundation from which to explore the olfactory recognition process and may be useful in the development of a new integrated pest management strategy targeting olfactory recognition of C. obducta.

Olfactory recognition of snake cues by fawn-footed mosaic-tailed rats Melomys cervinipes

Rodents rely on their sensitive olfactory systems to detect and respond to predators. We investigated the ability of a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes, to detect, recognise, and discriminate between two species of native snakes. We used snake sheds from a sympatric venomous red-bellied black snake Pseudechis porphyriacus and a non-sympatric non-venomous Stimson’s python Antaresia stimsoni. 20 mosaic-tailed rats each experienced three olfactory tests using a Y-maze. Rats were first exposed to one snake shed against a paper control, and then exposed to the other snake shed against a paper control. Which rat experienced which shed first was allocated randomly. Mosaic-tailed rats were then exposed to both sheds simultaneously. Rats could detect the snake sheds, spending longer investigating, and making more visits to, the sheds than the paper control. They also recognised the sheds as potentially dangerous, reducing their total investigation over time, but increasing their frequency of visits. However, rats did not discriminate between sheds, suggesting a general strategy for assessing the identity of reptilian predators.